Laminating two or more products together has long been used to form various insulating jacketing materials. Early efforts at producing such laminations consisted of adhering a fabric over a cement coating. Since then, various jacketing techniques have been developed which include a variety of insulating materials, such as fiberglass covered with 0.006" to 0.020" thick aluminum, flexible or rigid plastic, or vapor barrier paper jackets.
The plastic employed for such insulation jacketing materials has generally been formed of commercial grade rigid PVC. Rigid PVC has been selected because of good fabrication characteristics combined with its excellent chemical, vapor barrier and water proofing properties. Typically, the rigid PVC used in plastic insulation materials has a specific gravity of approximately 1.44.
Aluminum is the most abundant metal in the world. It is an ubiquitous material widely used in applications requiring light weight strength and also in applications having difficult conformational fabrication problems. The unusual combination of light weight and strength makes aluminum applicable for many uses that other metals cannot fill. Aluminum also has high ductility at elevated temperatures. Some aluminum alloys resist corrosion very well. Additionally, the strength and ductility of aluminum increase at subzero temperatures which is the opposite of iron and steel. Aluminum also offers excellent vapor barrier properties at thicknesses of as low as 0.0003".